We've all wanted to do it at one point or another. Either when creating our own workflow forms or when using Infopath to store business data in a SharePoint Form Library: A way to choose a manager, assistant or co worker using the people picker control.
It is really not that hard, once you realise that it is not called people picker but Contact Selector in Infopath. Available as an extra Active X control to place on your form.
Here a great short artcle by a fellow blogger on how to use the control.
In his blog he shows a screenshot of the finshed xlm schema where the fields themselves are repeating fields. no need for that though. simple non repeating fields within a repeating group is good enough.
Also you might want to have more than one selector on your page. Nothing simpler than that. Simply create a new base group (for example manager) and then right click the existing Person repeating group and choose Reference
Then choose the newly created group for the copy of the Person element